This program is a multidisciplinary approach to the study of the immunopathogenesis of immunodeficiency disease, allergic states, and graft-versus-host disease following bone marrow transplantation. B cell lines from immunodeficient patients will be studied for expression of Ig genes. T and B cells from patients with the Wiskott-Aldrich syndrome will be examined to understand the molecular basis of the glycophorin (gp 115) deficiency. The cellular basis of natural tolerance will be studied in congenic mice who are C5 deficient or C5 sufficient. The surface antigens of T cells of mice and man that are involved in lymphocyte toxicity will be defined by monoclonal antibodies. Control if Ia expression on murine and human macrophages will be investigated.